Chromatography columns have been used for years for the separation and/or purification of different materials such as proteins.
These columns are formed of three basic components; a column tube, a bottom fixed end and a top, movable end. See U.S. Pat. No. 4,350,595 and U.S. Pat. No. 6,139,732. The top end moves relative to the tube so as to be capable of removal for introduction and removal of chromatography media in the tube and to be capable of longitudinal travel into the tube to compress the media for use.
This top end however needs to be fixed at some point to the column in order to move relative to the column.
A first means for accomplishing this is to form a tube of high strength materials, including metals such as stainless steel or rigid structural plastics, such as acrylics or polymethylpentenes such as TPX® plastic available from Mitsui Petrochemical Industries Ltd Corporation of Japan. The tube has a flange at the upper end to which a top plate is attached to the column and a flange at the lower end to which a fixed bottom end is attached. The top, movable end is then attached to this top plate and travels relative to it in and out of the tube.
An example of this type of structure is shown in FIG. 1. The tube 2 has a bottom plate 4 fixed in place by bolts 6 attached to a flange 8 of the tube 2. A top plate 10 is fixed to a top flange 12 of the tube 2 by setscrews 13. A movable end 14 is centrally located in the top plate 10 and is capable, by movement of rod 16, of moving into or out of the tube 2.
As the end 14 moves into the tube 2 to compress the media bed 18 for use, longitudinal forces are carried from the end 14 to the rod 16 to the top plate 10 and then to the tube 2 itself.
The other alternative is shown in FIG. 2. It uses a series of rods 20 or screws closely aligned around the outside of the tube 24 to carry the longitudinal forces rather than the wall of the tube itself. This allows one to use less structurally rigid materials, such as glass or plastics, preferably acrylic or styrene, and to also use thinner walled tubes. All of this reduces the weight and cost of the device.
Most of the elements of that tube 24 of FIG. 2 are similar to those of FIG. 1. One has a movable top end plate 22, a bottom plate 26, attached to a fixed bottom end 27, flanges 28, either as part of the tube 24 or in this example as separate pieces to secure the fixed top plate 30 and bottom plate 26 to the tube 22. A rod 32 extends through the plate 30 and is connected to the movable end 22 by a handle 34. A bed of chromatography media 36 is compressed by the movement of the end 22. Also shown in FIG. 2 are a series of guide rods 36, which are used, in larger columns to keep the end 22 horizontal during movement. Plate 30 is normally affixed on flange 33 and attached by numerous mechanical fasteners 31.
Both of these designs have their limitations. The need to use rigid structural materials for the tube in the embodiment of FIG. 1 limits one's choices of materials and often is more expensive. Also, the materials used are not translucent so that one cannot view the interior of the column. Removing the movable end from the column, such as to add or remove media is a cumbersome task requiring the removal of the top plate and bolts in order to do so. Also, once removed, one must find a place to position these pieces (top plate 10, rod 16 and end 14) where they will not be damaged or contaminated.
The embodiment of FIG. 2 provides one with the ability to use translucent materials such as glass or acrylic; however, the rods (which typically number between 8 and 12 per column) obscure one's view. Moreover, it is even more cumbersome to disassemble. One must disconnect all of the mechanical fasteners 31 from the ends of the rods 20 before removing the top plate 30 and end assembly (22, 32, 34). It too suffers from having to find a place to put these pieces where they will not be damages or contaminated. Further, reassembly is difficult, as one needs to align each of the mechanical fasteners 31 into their respective hole in the top plate 30 and flange 33.
What is needed is a simpler and easier mechanism for handling the longitudinal load of a column and which allows one to easily assemble and disassemble the column as needed.
The present invention provides such a device.